Oki Okipage 8p, Maintenance Manual, Page: 130 / 190

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3. CIRCUIT DESCRIPTION
3.1 Outline
The circuit of OKIPAGE8p consists of a main control board, a main high voltage power supply
board, a sub-high voltage power supply board and a power supply unit. The block diagram is
shown in Fig. 3-1. The main control board controls the reception and transmission of data with
a host I/f and processes command analysis, bit image development, raster buffer read. It also
controls the engine and high voltage outputs.
(1) Reception control
The main control board has one parallel I/F port which is compliant to the IEEE 1284
specification.
The parallel I/F port can specify the following item when set by the control panel:
I-PRIME: Enabled/ Disabled
(2) Command analysis processing
The OKIPAGE8p printers support PCL5e (Hewlett Packard LJ6P compatible).
An edit task fetches data from the receive buffer, analizes commands, and reconstructs the
data in such a way that print data are aligned from up to down and from right to left; then it
writes the resultant data into a page buffer with such control data as print position coordinate,
font type, etc. added.
(3) Font Processing
When one page editing is finished, a developing task makes an engine start and fetches data
from the page buffer synchronizing with a printing operation; then it developes the fetched
data to a bit map as referring to data from a character generator, and writes the resultant data
into the raster buffer (of band buffer structure).
(4) Raster buffer read
As controlling the engine operation, an engine task sends data from the raster buffer to the
LED head.
(5) High voltage control (main, sub)
The high voltage control circuit in the CPU.
The high voltage power supply board generates high voltage outputs, and have sensors, LED for
display.
The power supply unit gen26VDC output, +5DC output.